European Journal of Radiology 56 (2005) 365–369 The value of ultrasonographic measurement in carpal tunnel syndrome in patients with negative electrodiagnostic tests Hasan Rifat Koyuncuoglu a , Suleyman Kutluhan a,∗ , Ahmet Yesildag b , Orhan Oyar b , Kezban Guler a , Ahmet Ozden b a Department of Neurology, School of Medicine, Suleyman Demirel University, Isparta, Turkey b Department of Radiology, School of Medicine, Suleyman Demirel University, Isparta, Turkey Received 5 March 2005; received in revised form 18 May 2005; accepted 20 May 2005 Abstract The diagnosis of carpal tunnel syndrome (CTS) is mainly based on clinical findings and electrodiagnostic tests (EDT). However, EDT results do not support clinical findings in some cases. It has been recently suggested that ultrasonography (US) can be used to diagnose CTS. In this study, we aimed to investigate whether US has a diagnostic value for CTS in patients with negative EDT findings or not. EDT was performed on 319 wrists with clinical CTS findings in electrophysiology laboratory. Median and ulnar nerve conduction velocities were measured in all cases and electromyography was performed in patient with tenar atrophy and having suspicion involvement of brachial plexus as EDT. Fifty-nine wrists with negative EDT (study group) and 30 wrists from 15 healthy individuals (control group) were examined using US. The mean of cross-sectional areas (CSAs) measurements were found 8.83 ± 3.05 mm 2 by tracing method (TM) and 8.51 ± 3.13 mm 2 by ellipsoid formula (EF) in study group, and 7.63 ± 1.52 mm 2 by TM and 7.66 ± 1.42 mm 2 by EF in control group. The differences between study group and control group according to both TM and EF were significant (t-test p = 0.0079, p = 0.0460, respectively). In study group, CSAs were larger than 10.5 mm 2 in 18 (30.51%) and 16 (27.12%) wrists according to TM and EF findings, respectively, and in only one wrist (3.33%) in control group by both TM and EF. The differences of ultrasonographic CTS numbers between study group and control group were significant (p = 0.0024 by TM, p =0.0086 by EF). We confirmed the usefulness of quantitative US assessment in the diagnosis of CTS in the patients with negative EDT findings. If EDT findings are inadequate to confirm the CTS in the patients with clinical CTS, US studies may be helpful to diagnose. © 2005 Elsevier Ireland Ltd. All rights reserved. Keywords: Carpal tunnel syndrome; Electrodiagnostic tests; Ultrasonography 1. Introduction Carpal tunnel syndrome (CTS) is a common cause of compression neuropathy occurred by consequence of com- pression of the median nerve as it passes through the carpal tunnel [1]. The diagnosis is usually based on the character- istic clinical symptoms and electrodiagnostic tests (EDT). Sometimes suspicious conditions may be seen in the clinical examination or EDT findings [2–5]. Although EDT is highly specific [6], false-negative results can be seen in variable ratio ∗ Corresponding author at: Aksu Cad. Celik Sitesi, B Blok, Daire 2, 32100 Isparta, Turkey. Tel.: +90 246 2327008; fax: +90 246 2370240. E-mail address: skutluhan@hotmail.com (S. Kutluhan). of 10–20%, and the accuracy of EDT for diagnosis of CTS has been estimated to be 80–90% [3,6–8]. EDT usually shows the level of the lesion, but they do not provide special informa- tion for the etiology about the nerve or its surrounding tissue. Ultrasonographic (US) examination of the median nerve in CTS has been proposed as a useful tool in addition to EDT in the diagnosis of CTS. It is determined that the increase in cross-sectional area (CSA) measurement of median nerve at the end of pisiform bone is a significant criterion in the diag- nosis of CTS [9–16]. The diagnosis of CTS was based on EDT findings in the recent studies which were performed on the diagnostic value of US in CTS. However, the diagnostic value of US has not been investigated in cases with clinically CTS but electrophysiologically normal. 0720-048X/$ – see front matter © 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrad.2005.05.013